Strategy to Identify Infants with Hypoxic Ischemic Encephalopathy for Therapeutic Hypothermia-A Retrospective Audit

Although there is a critical need for timely, accurate recognition of infants with hypoxic ischemic encephalopathy (HIE) eligible for therapeutic hypothermia (TH), there is little published literature that comprehensively validates strategies to achieve this. For the Mater Mothers' Hospital, a screening protocol combining use of umbilical cord gases according to obstetric criteria and other evidence of depression at birth with a decision aid (the HIE Trigger Tool (TT)) for at-risk infants was developed. We audited whether the protocol supported appropriate clinical decisions.

Obstetric records were searched from 1 January 2016 to 31 July 2022 for eligible infants. Neonatal records were examined to assess usage, determine outcomes (diagnosis of HIE or other neurological conditions, use of TH, mortality and neurodevelopmental outcomes) and detect any additional HIE cases.

Of 64,055 live births ≥35 weeks, 35.4% had cord gases taken. Of 580 eligible infants, the TT was applied to 498 (86.3%), 155 of whom screened positive for HIE (any severity). Of 76 infants with moderate or severe encephalopathy, 69 received TH. The other seven had contraindications to TH (n = 2), late presentations without any depression at birth (>6 h, n = 3) or other causes of their encephalopathy (n = 2). The TT (which per instructions was commenced by one hour of age) was used to identify 61 of the infants with moderate/severe encephalopathy, while 15 were diagnosed before it was applied. No infants who screened negative using the TT presented later with seizures or any other signs of moderate or severe HIE.

The protocol including cord gases and the HIE TT is an effective method of screening for acute HIE needing TH.